> 4. Classic Computer HOWTO's. I've been
sitting at home for a week
> inventing things to do and started writing a how to document detailing
> drive alignment for various disk drives (not even close to ready yet).
> Anyway, seems like a cool idea for those of you who know how to do things
> to detail them in a howto and help improve everyone's know-how. People
> keep asking, for example, how to convert TV to composite output. If
> you've got nothing better to do ;).
Composite of any kind are no
difference TV has it too internally!
That would be wonderful when TV is very high quality tube/circuit
board to begin with. I think that someone would cut in byond the
Tuner for composite.
Aligning the drives is touch and go, once in a while I was
successful. The rate is much better on screw type because it's easy
to tweak until it fails either side and plant it in exactly midway.
I always recheck it with series of formatted disks from fresh drives
finding the both sides to get enough consistent results.
Worst drives to align is split-belt type. That is far hard to do.
Most of time on these screw types distrance between scratch marks is
about less than 5 or so degrees. Lots of drives are all compatiable
mechanically and most of time far easier to find a good used similar
brand and swap the logic board that still works to a good mechanical
drive. Amiga 880k drives are really PC 720k drives with bit of
differences in logic board so the mechanical drive swapping the
boards to another is good idea. The pinout is very close too but I
still have not found the HOW-TO to hack the standard PC 720k drive
BTW, I know that compaq SLT series laptop always use Toshiba drives
which means you can replace the worn out mechanical part with good
ones but still keeping the logic board.
The latter is actually a big problem. Most of the time
I do things
'because that's obviously the thing to do' - i.e. I've done it many
before, and there are good reasons why (for example) the line output
transistor is the big one on the heatsink next to the flyback - but it's
difficult to remember this when you're writing a how-to.
crankerous capacitors too they does kill the HOT if the
signal is not cleaned up by those little capacitors. And capacitors
are used often to shape the waveforms to keep the tube image square
and nice. Better Grab the Bob's ESR meter, it spots the baddies
every time capacitance meter missed and excellent meter for
fractions of a ohm or less as well. That is useful in hi frequency
area where ESR values is important. I'm trying to get that ESR meter
too since I fix tons of switching PSU and monitors because it's so
inexpensive. About 60 USD and if anyone would like to, I have web
Disk drive alignment : I've read many documents
(and even a few books) on
how to do this without an alignment disk (typically by using a commercial
software master disk , finding where the signal falls off in each
direction , and setting the head midway between the two point). Without
exception, every method has failed. IMHO the only way to align a drive is
with the proper (expensive) alignment CE disk.
BIG LOUD OUCH!
I knew about that too, Those disks is too far expensive for few fixes
run to pay off in due time. :)
5.25" and 3.5" alignment disks are still available (but expect to pay $100
a time...). I can't find 3" (Amstrad, etc) or 8" alignment disks anywhere,
One day I'm going to rip apart an old 8" drive and put a micrometer on the
head assembly. I can then (hopefuly) record my own alignment disks using a
bit of simple electronics.
Well, better renew the mechanicals to assure tight
type does wear out especially the pin that rides in screw groove.
Not that hard if you can grab the pin real good firmly and pull and
rotate it 180 and reinstall. And lot of 3.5" especially new ones
are plain plastic bearings sliding on the smooth steel rods is the
worst wear. Those ones who uses bushings fares better.
All those oil and grease should be cheaned out and relubed again.
And BIGGEST hint hint HINT, the belt driven drives is still made for
those notebooks. Gak, I thought belt driven spindle is really no
longer in production or in new design, OH BOY, what a biggest
mistake! (Just fixed one recently.) Just in case anyone here, look
into your notebook and look around the (purplish coloured) hub, you
should see the black band, that's belt wound around it, spun by the
elcheapo PM motor. When you work on one someday you will find
there's is one fixed naked ball bearing idler for the belt.